/* @internal */
namespace ts.codefix {
    const fixName = "addVoidToPromise";
    const fixId = "addVoidToPromise";
    const errorCodes = [
        Diagnostics.Expected_0_arguments_but_got_1_Did_you_forget_to_include_void_in_your_type_argument_to_Promise.code
    ];
    registerCodeFix({
        errorCodes,
        fixIds: [fixId],
        getCodeActions(context) {
            const changes = textChanges.ChangeTracker.with(context, t => makeChange(t, context.sourceFile, context.span, context.program));
            if (changes.length > 0) {
                return [createCodeFixAction(fixName, changes, Diagnostics.Add_void_to_Promise_resolved_without_a_value, fixId, Diagnostics.Add_void_to_all_Promises_resolved_without_a_value)];
            }
        },
        getAllCodeActions(context: CodeFixAllContext) {
            return codeFixAll(context, errorCodes, (changes, diag) => makeChange(changes, diag.file, diag, context.program, new Set()));
        }
    });

    function makeChange(changes: textChanges.ChangeTracker, sourceFile: SourceFile, span: TextSpan, program: Program, seen?: Set<ParameterDeclaration>) {
        const node = getTokenAtPosition(sourceFile, span.start);
        if (!isIdentifier(node) || !isCallExpression(node.parent) || node.parent.expression !== node || node.parent.arguments.length !== 0) return;

        const checker = program.getTypeChecker();
        const symbol = checker.getSymbolAtLocation(node);

        // decl should be `new Promise((<decl>) => {})`
        const decl = symbol?.valueDeclaration;
        if (!decl || !isParameter(decl) || !isNewExpression(decl.parent.parent)) return;

        // no need to make this change if we have already seen this parameter.
        if (seen?.has(decl)) return;
        seen?.add(decl);

        const typeArguments = getEffectiveTypeArguments(decl.parent.parent);
        if (some(typeArguments)) {
            // append ` | void` to type argument
            const typeArgument = typeArguments[0];
            const needsParens = !isUnionTypeNode(typeArgument) && !isParenthesizedTypeNode(typeArgument) &&
                isParenthesizedTypeNode(factory.createUnionTypeNode([typeArgument, factory.createKeywordTypeNode(SyntaxKind.VoidKeyword)]).types[0]);
            if (needsParens) {
                changes.insertText(sourceFile, typeArgument.pos, "(");
            }
            changes.insertText(sourceFile, typeArgument.end, needsParens ? ") | void" : " | void");
        }
        else {
            // make sure the Promise is type is untyped (i.e., `unknown`)
            const signature = checker.getResolvedSignature(node.parent);
            const parameter = signature?.parameters[0];
            const parameterType = parameter && checker.getTypeOfSymbolAtLocation(parameter, decl.parent.parent);
            if (isInJSFile(decl)) {
                if (!parameterType || parameterType.flags & TypeFlags.AnyOrUnknown) {
                    // give the expression a type
                    changes.insertText(sourceFile, decl.parent.parent.end, `)`);
                    changes.insertText(sourceFile, skipTrivia(sourceFile.text, decl.parent.parent.pos), `/** @type {Promise<void>} */(`);
                }
            }
            else {
                if (!parameterType || parameterType.flags & TypeFlags.Unknown) {
                    // add `void` type argument
                    changes.insertText(sourceFile, decl.parent.parent.expression.end, "<void>");
                }
            }
        }
    }

    function getEffectiveTypeArguments(node: NewExpression) {
        if (isInJSFile(node)) {
            if (isParenthesizedExpression(node.parent)) {
                const jsDocType = getJSDocTypeTag(node.parent)?.typeExpression.type;
                if (jsDocType && isTypeReferenceNode(jsDocType) && isIdentifier(jsDocType.typeName) && idText(jsDocType.typeName) === "Promise") {
                    return jsDocType.typeArguments;
                }
            }
        }
        else {
            return node.typeArguments;
        }
    }
}